When a multitrack recording apparatus is made up of a portable recorder, the number of channels which can be loaded in the multitrack recording apparatus is limited by the size of a housing. A two-channel multitrack recording apparatus or a four-channel multitrack recording apparatus has hitherto been said to be realistic.
When the number of channels of the multitrack recording apparatus is increased, a hitherto-known method is to synchronize the plurality of tracks by connecting them with a cable. However, to this end, a plurality of multitrack recording apparatus of the same type must be prepared. Since the multitrack recording apparatus are generally, comparatively expensive, cost performance is low, and therefore the multitrack recording apparatus have not yet become prevalent.
It is mentioned in JP 2001-351366 A to connect a plurality of audio recorders by way of a serial transmission interface and to set one master recorder, thereby synchronizing operation of another slave recorder to operation of the master recorder.
It is mentioned in JP 2010-165403 A to connect two multitrack recording apparatus with each other by way of a USB cable and to exchange a packaged control message, thereby enabling performance of synchronized sound-recording operation.
All of these related-art techniques are intended to connect a plurality of recorders or multitrack recording apparatus with cables. Since the techniques are based on the premise of the plurality of recorders of the same type, the foregoing problems reside in the techniques.
In the meantime, the reality is that smartphones have recently become pervasive and that many users capture still images and moving images or record sounds with the smartphones.